685 research outputs found

    Factors in the biosynthesis of tryptophan and tyrosine by Lactobacillus arabinosus

    Get PDF
    The Lactobacillus arabinosus 17-5 response curve for anthranilic acid in the absence of tryptophan is characterized by regular increase in growth to about 100 micrograms per 10 milliliter culture, steady decrease to about 500 micrograms, nearly complete inhibition from 1000 to 5000 micrograms, and fair growth above 10,000 micrograms. The inhibition is prevented by low concentrations of indole or tryptophan or by allowing initiation of growth at lower levels of anthranilic acid. Although added at normally inhibitory levels, anthranilic acid is then converted to tryptophan and heavy growth ensues;The inhibition is believed to involve interference with some essential cellular process, possibly a step in the conversion of anthranilic acid to tryptophan;A mutant strain (designated L. arabinosus A) overgrows inhibited cultures in two to three days. This mutant apparently differs from L. arabinosus 17-5 only in its insensitivity to anthranilic acid at levels inhibitory to the latter strain;Five N-substituted anthranilic acid derivatives were tested for inhibition of or participation in tryptophan synthesis. No inhibition was observed, and such tryptophan activity as exists is apparently due to conversion to anthranilic acid. Similar tests of 5-methyl- and 5-chloroanthranilic acids and of o-chloro-, o-bromo-, and o-methylbenzoic acids revealed neither type of activity;Attempts to determine the course of the indole-tryptophan conversion were unsuccessful

    Derwentwater. Vol. I

    Get PDF
    Dialecto literario inglés. -- Pertenece a la colección 1800-1950 del Salamanca Corpus. -- Dialecto de Northumberland. -- Charles L. Atkinson, ?-?. -- A veces atribuido a Edward Duros, ?-?. -- Derwentwater, A tale of 1715, Vol. 1. -- 1830.[ES]Novela que se desarrolla en Northumberland y que contiene dialecto de Northumberland. [EN]Novel that takes place in Northumberland and which contains Northumberland dialect

    Derwentwater. Vol. 2

    Get PDF
    Dialecto literario inglés. -- Pertenece a la colección 1800-1950 del Salamanca Corpus. -- Dialecto de Northumberland. -- Charles L. Atkinson, ?-?. -- A veces atribuido a Edward Duros, ?-?. -- Derwentwater, A tale of 1715, Vol. 2. -- 1830.[ES] Novela que se desarrolla en Northumberland y que contiene dialecto de Northumberland. [EN] Novel that takes place in Northumberland and which contains Northumberland dialect

    The Effect of Information Feedback Upon Psychophysical Judgments

    Get PDF
    An analysis was made of the role of presentation schedules and information feedback on performance in a forced-choice signal detection task. The experimental results indicate that information feedback facilitates performance, but only for certain presentation schedules. The present study was designed to assess performance in a signal detection task under two conditions of information feedback. In the I-condition, S was told on each trial whether his detection response was correct or incorrect; in the !-condition S was given no feedback regarding the correctness of his response. The task involved a 2-response, forced-choice auditory detection problem. On each trial 2 temporal intervals were defined and S was required to report which interval he believed contained the signal; i. e., in one interval a tone burst in a background of white noise was presented, while the other interval contained only white noise. A trial will be denoted as s1 or s2, depending on whether the signal was embedded in the 1st or 2nd interval; the S's response will be denoted A1 or A2 to indicate which interval he reported contained the signal. The probability of an s1 trial will be denoted as y. In this study two values of y were used (.50 and.75) and, as indicated above, two conditions of information feedback. Thus there were 4 experimental conditions (501, 50I, 751, 75I); each S was run under all 4 conditions. Method Gaussian noise was presented binaurally in S's headphones throughout a test session and the signal was a 1000-cps sinusoid tone; the tone was presented for 100 msec. including equal fall and rise times of 20 msec. The ratio of signal energy to noise power in a unit bandwidth was 2.9, and was constant throughout the study. The. S was seated before a stimulus display board. On each trial a red warning light was flashed for 100 msec. Two amber lights then came on successively each for 1 sec.; these lights defined the 2 observation intervals. The onset of the signal occurred 500 msec. after the onset of one of the observation intervals. After the second amber light went off, S indicated his response by pressing 1 of 2 wand switches under cards reading "1st interval" and "2nd interval." For the !-condition a green light flashed on above the correct response key after S's response; the green light was omitted in the !-condition. Each trial lasted 6 sec. The S's were 12 male college students with normal hearing. They were run for two practice sessions followed by 20 test sessions. Test sessions were run on consecutive days, 350 trials/day. Each day S ran on 1 of the 4 experimental conditions; in successive 4-day blocks S ran one day on each of the 4 experimental conditions in a random order. Thus, over 20 days each of the experimental conditions was repeated 5 times

    Lingin Derived Organic Matter in Georgia Coastal Waters

    Get PDF
    The importance of riverine- and saltmarsh-derived organic matter to the food web of Georgia coastal waters has been a focus of ecological research over the past thirty years. Studies based on energy budgets, carbon flux measurements, and stable isotope ratios have generally implicated marsh detritus as an important, although not always dominant, source of organic matter within the marshes and adjacent estuaries (Teal 1962, Odum and de la Cruz 1967, Haines 1977, Peterson and Howarth 1987). However, data on the contribution of exported marsh and riverine organic matter to productivity futher offshore, in continental shelf waters off the coast of Georgia, remains equivocal (Chalmers et al. 1985, Hopkinson 1985). Dissolved lignin-derived compounds provide molecular level markers by which to determine the presence of terrestrially-derived organic matter in marine ecosystems. Lignin is found only in vascular plants and has no known oceanic sources. Thus its presence in seawater serves as unequivocal evidence of input of marsh or riverine organic matter, and indeed such lignin-derived material has been found in open ocean water a great distance from its probable point of origin (Meyers-Schulte and Hedges 1986). In this study, we present data on concentrations and distribution of lignin phenols in seawater samples collected during October and November 1987 on the continental shelf of the southeastern U.S., between Cape Hattaras and Cape Canaveral

    Sustainable Engineering Education Embedded Curricula Research Project

    Get PDF
    The SEFI Annual Conference is a scientific conference focused on Engineering Education and the biggest event of this type in Europe. SEFI Annual Conferences are a unique opportunity for professors, students, industry and profesional organisations to exchange their views and to meet their peers and create a European network of contacts. The topics of the conferences reflect the objectives of the society and the priorities identified by its members. The flagship European conference for engineering education is the annual conference of the European Society for Engineering Education (SEFI). Companies and organisations with an interest in engineering education are invited to support the 2023 SEFI Annual Conference. The theme for the conference will be Engineering Education for Sustainabilit

    Distribution of Terrestrially Derived Dissolved Organic Matter on the Southeastern United States Continental Shelf

    Get PDF
    Dissolved lignin-derived compounds in seawater indicate the presence of organic matter originating from vascular plants and therefore from terrestrial (upland and coastal marsh) ecosystems. We used a hydrophobic resin to concentrate lignin-rich humic substances and to determine concentrations of lignin oxidation products (vanillyl lignin phenols) for waters of the continental shelf of the southeastern U.S. Lignin phenol concentrations ranged from 0.05 to 4.2µg liter‒1 and accounted for 0.002–0.13% of the total dissolved organic carbon (DOC) pool in continental shelf waters. Dissolved lignin concentrations were generally highest near the shore and in those areas receiving greatest river and marsh discharge. Concentrations varied on both short-term (weekly) and seasonal time scales, however, indicating that the contribution of terrestrially derived dissolved organic matter to the C budget of the shelf is quite variable. Salinity (\u3e 31‰) was significantly correlated (negatively) with lignin phenol concentrations during three of four cruises, suggesting largely conservative mixing of lignin-derived material on the shelf In selected rivers and salt marshes contributing terrestrially derived organic matter to the continental shelf, lignin phenol C accounted for 0.14–1.0% of the DOC. A simple mixing model which assumes no biological or physical sinks of lignin-derived material during transport from terrestrial sources to the shelf predicts that an average of 6–36% of nearshore DOC derives from terrestrial ecosystems, depending on whether the terrestrial end-member (lignin source) is assumed to be a river or a salt marsh, while 5–26% of inner shelf DOC and 3–18% of mid- to outer-shelf DOC is of terrestrial origin

    Coding culture: challenges and recommendations for comparative cultural databases

    Get PDF
    Considerable progress in explaining cultural evolutionary dynamics has been made by applying rigorous models from the natural sciences to historical and ethnographic information collected and accessed using novel digital platforms. Initial results have clarified several long-standing debates in cultural evolutionary studies, such as population origins, the role of religion in the evolution of complex societies and the factors that shape global patterns of language diversity. However, future progress requires recognition of the unique challenges posed by cultural data. To address these challenges, standards for data collection, organisation and analysis must be improved and widely adopted. Here, we describe some major challenges to progress in the construction of large comparative databases of cultural history, including recognising the critical role of theory, selecting appropriate units of analysis, data gathering and sampling strategies, winning expert buy-in, achieving reliability and reproducibility in coding, and ensuring interoperability and sustainability of the resulting databases. We conclude by proposing a set of practical guidelines to meet these challenges

    Interaction of glycoprotein H of human herpesvirus 6 with the cellular receptor CD46.

    Get PDF
    Human herpesvirus 6 (HHV-6) employs the complement regulator CD46 (membrane cofactor protein) as a receptor for fusion and entry into target cells. Like other known herpesviruses, HHV-6 encodes multiple glycoproteins, several of which have been implicated in the entry process. In this report, we present evidence that glycoprotein H (gH) is the viral component responsible for binding to CD46. Antibodies to CD46 co-immunoprecipitated an approximately 110-kDa protein band specifically associated with HHV-6-infected cells. This protein was identified as gH by selective depletion with an anti-gH monoclonal antibody, as well as by immunoblot analysis with a rabbit hyperimmune serum directed against a gH synthetic peptide. In reciprocal experiments, a monoclonal antibody against HHV-6 gH was found to co-immunoprecipitate CD46. Studies using monoclonal antibodies directed against specific CD46 domains, as well as engineered constructs lacking defined CD46 regions, demonstrated a close correspondence between the CD46 domains involved in the interaction with gH and those previously shown to be critical for HHV-6 fusion (i.e. short consensus repeats 2 and 3)

    Health service delivery and workforce in northern Australia: a scoping review

    Get PDF
    Introduction: Delivering health services and improving health outcomes of the 1.3 million people residing in northern Australia, a region spanning 3 million km2 across the three jurisdictions of Western Australia, Northern Territory and Queensland, presents specific challenges. This review addresses a need for systems level analysis of the issues influencing the coverage, quality and responsiveness of health services across this region by examining the available published literature and identifying key policy-relevant gaps. Methods: A scoping review design was adopted with searches incorporating both peer-reviewed and grey literature (eg strategy documents, annual reports and budgets). Grey literature was predominantly sourced from websites of key organisations in the three northern jurisdictions, with peer-reviewed literature sourced from electronic database searches and reference lists. Key articles and documents were also contributed by health sector experts. Findings were synthesised and reported narratively using the WHO health system ‘building blocks’ to categorise the data. Results: From the total of 324 documents and data sources included in the review following screening and eligibility assessment, 197 were peer-reviewed journal articles and 127 were grey literature. Numerous health sector actors across the north – comprising planning bodies, universities and training organisations, peak bodies and providers – deliver primary, secondary and tertiary healthcare and workforce education and training in highly diverse contexts of care. Despite many exemplar health service and workforce models in the north, this synthesis describes a highly fragmented sector with many and disjointed stakeholders and funding sources. While the many strengths of the northern health system include expertise in training and supporting a fit-for-purpose health workforce, health systems in the north are struggling to meet the health needs of highly distributed populations with poorly targeted resources and ill-suited funding models. Ageing of the population and rising rates of chronic disease and mental health issues, underpinned by complex social, cultural and environmental determinants of health, continue to compound these challenges. Conclusion: Policy goals about developing northern Australia economically need to build from a foundation of a healthy and productive population. Improving health outcomes in the north requires political commitment, local leadership and targeted investment to improve health service delivery, workforce stability and evidence-based strengthening of community-led comprehensive primary health care. This requires intersectoral collaboration across many organisations and the three jurisdictions, drawing from previous collaborative experiences. Further evaluative research, linking structure to process and outcomes, and responding to changes in the healthcare landscape such as the rapid emergence of digital technologies, is needed across a range of policy areas to support these efforts
    • …
    corecore